Companies send large volumes of emails to customers in the form of email campaigns to market products and services. The emails often include advertisements, promotions, new products, and other information that inform potential customers and convince them to purchase or use a product or service.
Email campaigns are effective since they enable an advertiser to target a specific list of people, track user responses, and market products and services at a relatively low cost when compared with other marketing alternatives, such as massive postal mailings.
At the same time, email campaigns are often viewed as being spam or unsolicited bulk email since the recipient does not desire to receive the email. If a large number of recipients complain about receiving unwanted emails, then the advertiser can be blacklisted by the Internet Service Providers (ISPs) or email providers and prevented from distributing emails in the current and subsequent email campaigns. Furthermore, large email campaigns can be rather inefficient when only a tiny fraction of recipients respond to the email. An advertiser can also accumulatively spend a large sum of money to third-party email vendors for sending huge amount of emails.